Matrix metalloproteases ("MMPs") are a family of proteases (enzymes) involved in the degradation and remodeling of connective tissues. Members of this family of endopeptidase enzymes are secreted as proenzymes from various cell types that reside in or are associated with connective tissue, such as fibroblasts, monocytes, macrophages, endothelial cells, and invasive or metastatic tumor cells. MMP expression is stimulated by growth factors and cytokines in the local tissue environment, where these enzymes act to specifically degrade protein components of the extracellular matrix, such as collagen, proteoglycans (protein core), fibronectin and laminin. These ubiquitous extracellular matrix components are present in the linings ofjoints, interstitial connective tissues, basement membranes and cartilage.
The MMPs share a number of properties, including zinc and calcium dependence, secretion as zymogens, and 40-50% amino acid sequence homology. Eleven metalloenzymes have been well-characterized as MMP's in humans, including three collagenases, three stromelysins, two gelatinases, matrilysin, metalloelastase, and membrane-type MMP, as discussed in greater detail below.
Interstitial collagenases catalyze the initial and rate-limiting cleavage of native collagen types I, II and III. Collagen, the major structural protein of mammals, is an essential component of the matrix of many tissues, for example, cartilage, bone, tendon and skin. Interstitial collagenases are very specific matrix metalloproteases which cleave these collagens to give two fragments which spontaneously denature at physiological temperatures and therefore become susceptible to cleavage by less specific enzymes. Cleavage by the collagenases results in the loss of structural integrity of the target tissue, essentially an irreversible process. There are currently three known human collagenases, the first two of which are relatively well-characterized (FASEB J., 5, 2145-54 (1991)). Human fibroblast-type collagenase (HFC, MMP-1, or collagenase-1) is produced by a wide variety of cells including fibroblasts and macrophages. Human neutrophil-type collagenase (HNC, MMP-8, or collagenase-2) has so far only been demonstrated to be produced by neutrophils. The most recently discovered member of this group of MMPs is human collagenase-3 (MMP-13), which was originally found in breast carcinomas (J. Biol. Chem., 269, 16,766-16,773)(1994)), but has since shown to be produced by chondrocytes (J. Clin. Invest., 97, 761-768, 1996).
The gelatinases include two distinct, but highly related, enzymes: a 72-kD enzyme (gelatinase A, HFG, MMP-2) secreted by fibroblasts and a wide variety of other cell types, and a 92-kD enzyme (gelatinase B, HNG, MMP-9) released by mononuclear phagocytes, neutrophils, corneal epithelial cells, tumor cells, cytotrophoblasts and keratinocytes. These gelatinases have been shown to degrade gelatins (denatured collagens), collagen types IV (basement membrane) and V, fibronectin and insoluble elastin.
Stromelysins 1 and 2 have been shown to cleave a broad range of matrix substrates, including laminin, fibronectin, proteoglycans, and collagen types IV and IX in their non-helical domains.
Matrilysin (MMP-7, PUMP-1) has been shown to degrade a wide range of matrix substrates including proteoglycans, gelatins, fibronectin, elastin and laminin. Its expression has been documented in mononuclear phagocytes, rate uterine explants and sporadically in tumors. Other less characterized MMPs include macrophage metalloelastase (MME, MMP-12), membrane type MMP (MMP-14), and stromelysin-3 (MMP-11).
Excessive degradation of extracellular matrix by MMPs is implicated in the pathogenesis of many diseases of both chronic and acute nature. For example, numerous studies, as reviewed in Exp. Opin. Invest. Drugs, 5, 323-335, (1996), have established that expression and activation of MMPs are critical events in tumor growth, invasion and metastasis. In addition, MMP activity has been found to be required for angiogenesis, which is necessary for tumor growth as well for other pathological conditions such as macular degeneration.
MMPs, especially stromelysin-1, collagenases-1, and collagenase-3, have been strongly implicated in the destruction of articular cartilage that is the hallmark of rheumatoid arthritis and osteoarthritis. See, for example, J. Clin. Invest., 97, 761-768 (1996). In addition, the tissue destruction associated with gingivitis and periodontal disease is believed to be mediated by overexpression of MMPs in response to proinflammatory cytokines. See Molecular Pathogenesis of Periodontal Disease, Ch. 17, 191-202 (1994). Other diseases in which critical roles for MMPs have been identified include multiple sclerosis (J. Neuroimmunol., 41, 29-34 (1992)), corneal ulceration (Invest. Opthalmol and Visual Sci., 32, 1569-1575 (1989)), stroke (Brain Research, 703, 151-155 (1995) and J. Cereb. Blood Flow Metab., 16, 360-366 (1996)), sun-induced skin ageing (Nature, 379, 335-339 (1996)), chronic obstructive pulmonary disease, such as emphysema (Am. J. Respir. Cell. Mol. Biol. 7, 5160-5165 (1994)), chronic ulceration (J. Clin. Invest., 94, 79-88 (1994)), cardiac arrhythmia, and endometriosis. Finally, roles for MMP-mediated degradation of basement membranes have been proposed in the rupture of atherosclerotic plaques (Basic Res. Cardiol., 89(SUPPL. 1), 59-70, (1994)) and in the development of glomerular disease (J. Clin. Invest., 97, 1094-1101 (1996)).
Inhibitors of MMPs are expected to provide useful treatments for the diseases described above in which degradation of the extracellular matrix by MMPs contributes to the pathogenesis of the disease. In general, selective MMP inhibitors of particular subsets of MMPs may offer therapeutic advantages, as it has been typically observed that a limited number of members of the MMP family are involved in any one of the disease states listed above. For example, the involvement of individual collagenases in the degradation of tissue collagens probably depends markedly on the tissue. The tissue distribution of human collagenases suggests that collagenase-3 is the major participant in the degradation of the collagen matrix of cartilage, while collagenase-1 is more likely to be involved in tissue remodeling of skin and other soft tissues. In addition, stromelysin-1 appears to be largely responsible for excessive loss of proteoglycan from cartilage. Thus, the inventive compounds disclosed herein that are selective inhibitors for collagenase-3 and stromelysin over collagenase-1 are preferred for treatment of diseases associated with cartilage erosion, such as rheumatoid and osteoarthritis. Similarly, among the MMPs, metalloelastase has been specifically implicated in the pathology of pulmonary emphysema. See J. Biol. Chem. 270, 14568-14575 (1995).
The design and uses of MMP inhibitors are reviewed, for example, in J. Enzyme Inhibition, 2, 1-22 (1987); Progress in Medicinal Chemistry 29, 271-334 (1992); Current Medicinal Chemistry, 2, 743-762 (1995); Exp. Opin. Ther. Patents, 5, 1287-1296 (1995); and Drug Discovery Today, 1, 16-26 (1996). MMP inhibitors are also the subject of numerous patents and patent applications. In the majority of these publications, the preferred inventive compounds are hydroxamic acids, as it has been well-established that the hydroxamate function is the optimal zinc-coordinating functionality for binding to the active site of MMPs. For example, the hydroxamate inhibitors described in the literature are generally 100 to 1000-fold more potent than the correponding inhibitors wherein the hydroxamic acid functionality is replaced by a carboxylic acid functionality. Nevertheless, hydroxamic acids tend to exhibit relatively poor bioavailability. The preferred compounds disclosed herein are carboxylic acid inhibitors that possess inhibitory potency against certain of the MMPs that is comparable to the potency of the hydroxamic acid inhibitors that have been reported in the literature. The following patents and patent applications disclose carboxylic acid inhibitiors that are, as are the inventive carboxylic acid inhibitors disclosed herein, monoamine derivatives of substituted succinic acids: Celltech Ltd.: EP-A-0489577 (WO 92/099565), EP-A-0489579, WO 93/24475, WO 93/244449; British Biotech Pharameuticals Ltd.: WO 95/32944, WO 95/19961; Sterling Winthrop, Inc.: U.S. Pat. No. 5,256,657; Sanofi Winthrop, Inc.: WO 95/22966; and Syntex (U.S.A.) Inc. WO 94/04735, WO 95/12603, and WO 96/16027.